Elucidation of the roles of various enzymes in both normal and abnormal physiological states has led to an increasing demand for convenient, rapid and reliable techniques of assaying for specific enzymes. Such assays are valuable tools in diagnosis, in monitoring effectiveness of drugs and other pharmacological agents and in the further study of the enzymes per se, their capabilities and their physiological effects.
The need for rapid, reliable and precise assays for enzymes indigenous to the renin-angiotensin system has grown as more has been learned about the part which the system and its individual enzymes play in the regulation of blood pressure, and the ways in which inhibitors of specific enzymes present in the system may aid in such regulation.
Presently known assays for such enzymes are in most instances inefficient, procedurally cumbersome and timeconsuming, requiring many manipulative steps which may adversely effect the precision and accuracy of the results. Those which depend upon the use of radioactive tags such as .sup.14 C or .sup.3 H are frequently disadvantageous because of current problems in disposing of radioactive waste; those which depend upon non-radioactive fluorescent or colorimetric tags are frequently low in sensitivity and, hence, are wanting in precision and accuracy.
Throughout the specification, the following symbols have the significance shown in the table:
TABLE 1 ______________________________________ Ala = L-alanine Arg = L-arginine Asp = L-aspartic acid Gln = L-glutamine &lt;Glu = pyro-L-glutamic acid Gly = glycine Hip = Hippuric acid (Benzoyl glycine) His = L-histidine Ile = L-isoleucine Leu = L-leucine Lys = L-lysine Phe = L-phenylalanine Pro = L-proline Ser = L-serine Trp = L-tryptophan Tyr = L-tyrosine Val = L-valine ACE = Angiotensin converting enzyme Bicine = N,N--bis (2-hydroxyethyl) glycine EDTA = Ethylene diamine tetraacetic acid Hepes = N--2-hydroxyethylpiperazine-N'--2- ethanesulfonic acid HPP = p-hydroxyphenylpropionyl ______________________________________